a. Field of the Invention
This invention relates generally to the field of medical instruments, and more particularly to a cannula having a radiopaque portion, for use during medical procedures.
b. Description of the Related Art
Several medical procedures require the introduction of one or more medical instruments into arteries or veins so that the medical instruments may be advanced to a body location requiring, for example, diagnosis or treatment. Various types of cannula, for example, sheaths and catheters, are often introduced into a patient's body to perform medical procedures. The term “sheath” is generally applied to a cannula through which other medical instruments (for example, catheters, guidewires, leads, and dilators) are inserted and introduced within the body for manipulation. When used as a conduit to introduce other medical devices, the cannula is often referred to as an “introducer sheath.” The sheath effectively acts as a conduit, preventing damage to the wall of the vein or artery into which it is inserted. Similarly, the sheath may protect the region of the body to be diagnosed and/or treated. A hemostasis valve may be mounted to the proximal end of the sheath located outside the patient's body in order to inhibit leakage of blood flowing through the sheath.
In many medical procedures, the location of the sheath tip is important, insofar as the sheath must extend to the portion of the patient's body being diagnosed or treated. For example, ablation of a patient's heart requires precise placement of a catheter. Oftentimes, the catheter or sheath tip is tracked or located by electrophysiological guidance, fluoroscopy, or a combination of the two. In order to accurately track the distal tip of the catheter with fluoroscopy, a radiopaque material (i.e., a material reflecting or opaque to x-rays) is typically incorporated into the catheter tip in some fashion. The radiopaque material generally takes the form of a coating or solid, metallic ring.
Many times, introducer sheaths or cannulas are also splittable. That is, they may be torn apart longitudinally while removed from a patient's body in order to more rapidly remove the sheath, and thus limit blood loss. However, the radiopaque material often inhibits splitting of the introducer sheath, especially when the radiopaque substance is in the form of a solid metal ring. Even coatings applied to a sheath may reduce the sheath's ability to split apart. Thus, many current introducer sheaths compromise between quick removal and detectability via x-rays during procedures. Accordingly, there is a need for an improved introducer sheath having a radiopaque marker.
The information included in this Background section of the specification, including any references cited herein and any description or discussion thereof, is included for technical reference purposes only and is not to be regarded subject matter by which the scope of the invention is to be bound.